/**
 * @license
 * Copyright 2021 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// This file is automatically generated. Do not modify it.

import * as colorUtils from '../utils/color_utils';
import * as mathUtils from '../utils/math_utils';

import {Cam16} from './cam16';
import {ViewingConditions} from './viewing_conditions';


// material_color_utilities is designed to have a consistent API across
// platforms and modular components that can be moved around easily. Using a
// class as a namespace facilitates this.
//
// tslint:disable:class-as-namespace
/**
 * A class that solves the HCT equation.
 */
export class HctSolver {
  static SCALED_DISCOUNT_FROM_LINRGB = [
    [
      0.001200833568784504,
      0.002389694492170889,
      0.0002795742885861124,
    ],
    [
      0.0005891086651375999,
      0.0029785502573438758,
      0.0003270666104008398,
    ],
    [
      0.00010146692491640572,
      0.0005364214359186694,
      0.0032979401770712076,
    ],
  ];

  static LINRGB_FROM_SCALED_DISCOUNT = [
    [
      1373.2198709594231,
      -1100.4251190754821,
      -7.278681089101213,
    ],
    [
      -271.815969077903,
      559.6580465940733,
      -32.46047482791194,
    ],
    [
      1.9622899599665666,
      -57.173814538844006,
      308.7233197812385,
    ],
  ];

  static Y_FROM_LINRGB = [0.2126, 0.7152, 0.0722];

  static CRITICAL_PLANES = [
    0.015176349177441876, 0.045529047532325624, 0.07588174588720938,
    0.10623444424209313,  0.13658714259697685,  0.16693984095186062,
    0.19729253930674434,  0.2276452376616281,   0.2579979360165119,
    0.28835063437139563,  0.3188300904430532,   0.350925934958123,
    0.3848314933096426,   0.42057480301049466,  0.458183274052838,
    0.4976837250274023,   0.5391024159806381,   0.5824650784040898,
    0.6277969426914107,   0.6751227633498623,   0.7244668422128921,
    0.775853049866786,    0.829304845476233,    0.8848452951698498,
    0.942497089126609,    1.0022825574869039,   1.0642236851973577,
    1.1283421258858297,   1.1946592148522128,   1.2631959812511864,
    1.3339731595349034,   1.407011200216447,    1.4823302800086415,
    1.5599503113873272,   1.6398909516233677,   1.7221716113234105,
    1.8068114625156377,   1.8938294463134073,   1.9832442801866852,
    2.075074464868551,    2.1693382909216234,   2.2660538449872063,
    2.36523901573795,     2.4669114995532007,   2.5710888059345764,
    2.6777882626779785,   2.7870270208169257,   2.898822059350997,
    3.0131901897720907,   3.1301480604002863,   3.2497121605402226,
    3.3718988244681087,   3.4967242352587946,   3.624204428461639,
    3.754355295633311,    3.887192587735158,    4.022731918402185,
    4.160988767090289,    4.301978482107941,    4.445716283538092,
    4.592217266055746,    4.741496401646282,    4.893568542229298,
    5.048448422192488,    5.20615066083972,     5.3666897647573375,
    5.5300801301023865,   5.696336044816294,    5.865471690767354,
    6.037501145825082,    6.212438385869475,    6.390297286737924,
    6.571091626112461,    6.7548350853498045,   6.941541251256611,
    7.131223617812143,    7.323895587840543,    7.5195704746346665,
    7.7182615035334345,   7.919981813454504,    8.124744458384042,
    8.332562408825165,    8.543448553206703,    8.757415699253682,
    8.974476575321063,    9.194643831691977,    9.417930041841839,
    9.644347703669503,    9.873909240696694,    10.106627003236781,
    10.342513269534024,   10.58158024687427,    10.8238400726681,
    11.069304815507364,   11.317986476196008,   11.569896988756009,
    11.825048221409341,   12.083451977536606,   12.345119996613247,
    12.610063955123938,   12.878295467455942,   13.149826086772048,
    13.42466730586372,    13.702830557985108,   13.984327217668513,
    14.269168601521828,   14.55736596900856,    14.848930523210871,
    15.143873411576273,   15.44220572664832,    15.743938506781891,
    16.04908273684337,    16.35764934889634,    16.66964922287304,
    16.985093187232053,   17.30399201960269,    17.62635644741625,
    17.95219714852476,    18.281524751807332,   18.614349837764564,
    18.95068293910138,    19.290534541298456,   19.633915083172692,
    19.98083495742689,    20.331304511189067,   20.685334046541502,
    21.042933821039977,   21.404114048223256,   21.76888489811322,
    22.137256497705877,   22.50923893145328,    22.884842241736916,
    23.264076429332462,   23.6469514538663,     24.033477234264016,
    24.42366364919083,    24.817520537484558,   25.21505769858089,
    25.61628489293138,    26.021211842414342,   26.429848230738664,
    26.842203703840827,   27.258287870275353,   27.678110301598522,
    28.10168053274597,    28.529008062403893,   28.96010235337422,
    29.39497283293396,    29.83362889318845,    30.276079891419332,
    30.722335150426627,   31.172403958865512,   31.62629557157785,
    32.08401920991837,    32.54558406207592,    33.010999283389665,
    33.4802739966603,     33.953417292456834,   34.430438229418264,
    34.911345834551085,   35.39614910352207,    35.88485700094671,
    36.37747846067349,    36.87402238606382,    37.37449765026789,
    37.87891309649659,    38.38727753828926,    38.89959975977785,
    39.41588851594697,    39.93615253289054,    40.460400508064545,
    40.98864111053629,    41.520882981230194,   42.05713473317016,
    42.597404951718396,   43.141702194811224,   43.6900349931913,
    44.24241185063697,    44.798841244188324,   45.35933162437017,
    45.92389141541209,    46.49252901546552,    47.065252796817916,
    47.64207110610409,    48.22299226451468,    48.808024568002054,
    49.3971762874833,     49.9904556690408,     50.587870934119984,
    51.189430279724725,   51.79514187861014,    52.40501387947288,
    53.0190544071392,     53.637271562750364,   54.259673423945976,
    54.88626804504493,    55.517063457223934,   56.15206766869424,
    56.79128866487574,    57.43473440856916,    58.08241284012621,
    58.734331877617365,   59.39049941699807,    60.05092333227251,
    60.715611475655585,   61.38457167773311,    62.057811747619894,
    62.7353394731159,     63.417162620860914,   64.10328893648692,
    64.79372614476921,    65.48848194977529,    66.18756403501224,
    66.89098006357258,    67.59873767827808,    68.31084450182222,
    69.02730813691093,    69.74813616640164,    70.47333615344107,
    71.20291564160104,    71.93688215501312,    72.67524319850172,
    73.41800625771542,    74.16517879925733,    74.9167682708136,
    75.67278210128072,    76.43322770089146,    77.1981124613393,
    77.96744375590167,    78.74122893956174,    79.51947534912904,
    80.30219030335869,    81.08938110306934,    81.88105503125999,
    82.67721935322541,    83.4778813166706,     84.28304815182372,
    85.09272707154808,    85.90692527145302,    86.72564993000343,
    87.54890820862819,    88.3767072518277,     89.2090541872801,
    90.04595612594655,    90.88742016217518,    91.73345337380438,
    92.58406282226491,    93.43925555268066,    94.29903859396902,
    95.16341895893969,    96.03240364439274,    96.9059996312159,
    97.78421388448044,    98.6670533535366,     99.55452497210776,
  ];

  /**
   * Sanitizes a small enough angle in radians.
   *
   * @param angle An angle in radians; must not deviate too much
   * from 0.
   * @return A coterminal angle between 0 and 2pi.
   */
  private static sanitizeRadians(angle: number): number {
    return (angle + Math.PI * 8) % (Math.PI * 2);
  }

  /**
   * Delinearizes an RGB component, returning a floating-point
   * number.
   *
   * @param rgbComponent 0.0 <= rgb_component <= 100.0, represents
   * linear R/G/B channel
   * @return 0.0 <= output <= 255.0, color channel converted to
   * regular RGB space
   */
  private static trueDelinearized(rgbComponent: number): number {
    const normalized = rgbComponent / 100.0;
    let delinearized = 0.0;
    if (normalized <= 0.0031308) {
      delinearized = normalized * 12.92;
    } else {
      delinearized = 1.055 * Math.pow(normalized, 1.0 / 2.4) - 0.055;
    }
    return delinearized * 255.0;
  }

  private static chromaticAdaptation(component: number): number {
    const af = Math.pow(Math.abs(component), 0.42);
    return mathUtils.signum(component) * 400.0 * af / (af + 27.13);
  }

  /**
   * Returns the hue of a linear RGB color in CAM16.
   *
   * @param linrgb The linear RGB coordinates of a color.
   * @return The hue of the color in CAM16, in radians.
   */
  private static hueOf(linrgb: number[]): number {
    const scaledDiscount =
        mathUtils.matrixMultiply(linrgb, HctSolver.SCALED_DISCOUNT_FROM_LINRGB);
    const rA = HctSolver.chromaticAdaptation(scaledDiscount[0]);
    const gA = HctSolver.chromaticAdaptation(scaledDiscount[1]);
    const bA = HctSolver.chromaticAdaptation(scaledDiscount[2]);
    // redness-greenness
    const a = (11.0 * rA + -12.0 * gA + bA) / 11.0;
    // yellowness-blueness
    const b = (rA + gA - 2.0 * bA) / 9.0;
    return Math.atan2(b, a);
  }

  private static areInCyclicOrder(a: number, b: number, c: number): boolean {
    const deltaAB = HctSolver.sanitizeRadians(b - a);
    const deltaAC = HctSolver.sanitizeRadians(c - a);
    return deltaAB < deltaAC;
  }

  /**
   * Solves the lerp equation.
   *
   * @param source The starting number.
   * @param mid The number in the middle.
   * @param target The ending number.
   * @return A number t such that lerp(source, target, t) = mid.
   */
  private static intercept(source: number, mid: number, target: number):
      number {
    return (mid - source) / (target - source);
  }

  private static lerpPoint(source: number[], t: number, target: number[]):
      number[] {
    return [
      source[0] + (target[0] - source[0]) * t,
      source[1] + (target[1] - source[1]) * t,
      source[2] + (target[2] - source[2]) * t,
    ];
  }

  /**
   * Intersects a segment with a plane.
   *
   * @param source The coordinates of point A.
   * @param coordinate The R-, G-, or B-coordinate of the plane.
   * @param target The coordinates of point B.
   * @param axis The axis the plane is perpendicular with. (0: R, 1:
   * G, 2: B)
   * @return The intersection point of the segment AB with the plane
   * R=coordinate, G=coordinate, or B=coordinate
   */
  private static setCoordinate(
      source: number[],
      coordinate: number,
      target: number[],
      axis: number,
      ): number[] {
    const t = HctSolver.intercept(source[axis], coordinate, target[axis]);
    return HctSolver.lerpPoint(source, t, target);
  }

  private static isBounded(x: number): boolean {
    return 0.0 <= x && x <= 100.0;
  }

  /**
   * Returns the nth possible vertex of the polygonal intersection.
   *
   * @param y The Y value of the plane.
   * @param n The zero-based index of the point. 0 <= n <= 11.
   * @return The nth possible vertex of the polygonal intersection
   * of the y plane and the RGB cube, in linear RGB coordinates, if
   * it exists. If this possible vertex lies outside of the cube,
   * [-1.0, -1.0, -1.0] is returned.
   */
  private static nthVertex(y: number, n: number): number[] {
    const kR = HctSolver.Y_FROM_LINRGB[0];
    const kG = HctSolver.Y_FROM_LINRGB[1];
    const kB = HctSolver.Y_FROM_LINRGB[2];
    const coordA = n % 4 <= 1 ? 0.0 : 100.0;
    const coordB = n % 2 === 0 ? 0.0 : 100.0;
    if (n < 4) {
      const g = coordA;
      const b = coordB;
      const r = (y - g * kG - b * kB) / kR;
      if (HctSolver.isBounded(r)) {
        return [r, g, b];
      } else {
        return [-1.0, -1.0, -1.0];
      }
    } else if (n < 8) {
      const b = coordA;
      const r = coordB;
      const g = (y - r * kR - b * kB) / kG;
      if (HctSolver.isBounded(g)) {
        return [r, g, b];
      } else {
        return [-1.0, -1.0, -1.0];
      }
    } else {
      const r = coordA;
      const g = coordB;
      const b = (y - r * kR - g * kG) / kB;
      if (HctSolver.isBounded(b)) {
        return [r, g, b];
      } else {
        return [-1.0, -1.0, -1.0];
      }
    }
  }

  /**
   * Finds the segment containing the desired color.
   *
   * @param y The Y value of the color.
   * @param targetHue The hue of the color.
   * @return A list of two sets of linear RGB coordinates, each
   * corresponding to an endpoint of the segment containing the
   * desired color.
   */
  private static bisectToSegment(y: number, targetHue: number): number[][] {
    let left = [-1.0, -1.0, -1.0];
    let right = left;
    let leftHue = 0.0;
    let rightHue = 0.0;
    let initialized = false;
    let uncut = true;
    for (let n = 0; n < 12; n++) {
      const mid = HctSolver.nthVertex(y, n);
      if (mid[0] < 0) {
        continue;
      }
      const midHue = HctSolver.hueOf(mid);
      if (!initialized) {
        left = mid;
        right = mid;
        leftHue = midHue;
        rightHue = midHue;
        initialized = true;
        continue;
      }
      if (uncut || HctSolver.areInCyclicOrder(leftHue, midHue, rightHue)) {
        uncut = false;
        if (HctSolver.areInCyclicOrder(leftHue, targetHue, midHue)) {
          right = mid;
          rightHue = midHue;
        } else {
          left = mid;
          leftHue = midHue;
        }
      }
    }
    return [left, right];
  }

  private static midpoint(a: number[], b: number[]): number[] {
    return [
      (a[0] + b[0]) / 2,
      (a[1] + b[1]) / 2,
      (a[2] + b[2]) / 2,
    ];
  }

  private static criticalPlaneBelow(x: number): number {
    return Math.floor(x - 0.5);
  }

  private static criticalPlaneAbove(x: number): number {
    return Math.ceil(x - 0.5);
  }

  /**
   * Finds a color with the given Y and hue on the boundary of the
   * cube.
   *
   * @param y The Y value of the color.
   * @param targetHue The hue of the color.
   * @return The desired color, in linear RGB coordinates.
   */
  private static bisectToLimit(y: number, targetHue: number): number[] {
    const segment = HctSolver.bisectToSegment(y, targetHue);
    let left = segment[0];
    let leftHue = HctSolver.hueOf(left);
    let right = segment[1];
    for (let axis = 0; axis < 3; axis++) {
      if (left[axis] !== right[axis]) {
        let lPlane = -1;
        let rPlane = 255;
        if (left[axis] < right[axis]) {
          lPlane = HctSolver.criticalPlaneBelow(
              HctSolver.trueDelinearized(left[axis]));
          rPlane = HctSolver.criticalPlaneAbove(
              HctSolver.trueDelinearized(right[axis]));
        } else {
          lPlane = HctSolver.criticalPlaneAbove(
              HctSolver.trueDelinearized(left[axis]));
          rPlane = HctSolver.criticalPlaneBelow(
              HctSolver.trueDelinearized(right[axis]));
        }
        for (let i = 0; i < 8; i++) {
          if (Math.abs(rPlane - lPlane) <= 1) {
            break;
          } else {
            const mPlane = Math.floor((lPlane + rPlane) / 2.0);
            const midPlaneCoordinate = HctSolver.CRITICAL_PLANES[mPlane];
            const mid =
                HctSolver.setCoordinate(left, midPlaneCoordinate, right, axis);
            const midHue = HctSolver.hueOf(mid);
            if (HctSolver.areInCyclicOrder(leftHue, targetHue, midHue)) {
              right = mid;
              rPlane = mPlane;
            } else {
              left = mid;
              leftHue = midHue;
              lPlane = mPlane;
            }
          }
        }
      }
    }
    return HctSolver.midpoint(left, right);
  }

  private static inverseChromaticAdaptation(adapted: number): number {
    const adaptedAbs = Math.abs(adapted);
    const base = Math.max(0, 27.13 * adaptedAbs / (400.0 - adaptedAbs));
    return mathUtils.signum(adapted) * Math.pow(base, 1.0 / 0.42);
  }

  /**
   * Finds a color with the given hue, chroma, and Y.
   *
   * @param hueRadians The desired hue in radians.
   * @param chroma The desired chroma.
   * @param y The desired Y.
   * @return The desired color as a hexadecimal integer, if found; 0
   * otherwise.
   */
  private static findResultByJ(hueRadians: number, chroma: number, y: number):
      number {
    // Initial estimate of j.
    let j = Math.sqrt(y) * 11.0;
    // ===========================================================
    // Operations inlined from Cam16 to avoid repeated calculation
    // ===========================================================
    const viewingConditions = ViewingConditions.DEFAULT;
    const tInnerCoeff =
        1 / Math.pow(1.64 - Math.pow(0.29, viewingConditions.n), 0.73);
    const eHue = 0.25 * (Math.cos(hueRadians + 2.0) + 3.8);
    const p1 =
        eHue * (50000.0 / 13.0) * viewingConditions.nc * viewingConditions.ncb;
    const hSin = Math.sin(hueRadians);
    const hCos = Math.cos(hueRadians);
    for (let iterationRound = 0; iterationRound < 5; iterationRound++) {
      // ===========================================================
      // Operations inlined from Cam16 to avoid repeated calculation
      // ===========================================================
      const jNormalized = j / 100.0;
      const alpha =
          chroma === 0.0 || j === 0.0 ? 0.0 : chroma / Math.sqrt(jNormalized);
      const t = Math.pow(alpha * tInnerCoeff, 1.0 / 0.9);
      const ac = viewingConditions.aw *
          Math.pow(
              jNormalized,
              1.0 / viewingConditions.c / viewingConditions.z,
          );
      const p2 = ac / viewingConditions.nbb;
      const gamma = 23.0 * (p2 + 0.305) * t /
          (23.0 * p1 + 11 * t * hCos + 108.0 * t * hSin);
      const a = gamma * hCos;
      const b = gamma * hSin;
      const rA = (460.0 * p2 + 451.0 * a + 288.0 * b) / 1403.0;
      const gA = (460.0 * p2 - 891.0 * a - 261.0 * b) / 1403.0;
      const bA = (460.0 * p2 - 220.0 * a - 6300.0 * b) / 1403.0;
      const rCScaled = HctSolver.inverseChromaticAdaptation(rA);
      const gCScaled = HctSolver.inverseChromaticAdaptation(gA);
      const bCScaled = HctSolver.inverseChromaticAdaptation(bA);
      const linrgb = mathUtils.matrixMultiply(
          [rCScaled, gCScaled, bCScaled],
          HctSolver.LINRGB_FROM_SCALED_DISCOUNT,
      );
      // ===========================================================
      // Operations inlined from Cam16 to avoid repeated calculation
      // ===========================================================
      if (linrgb[0] < 0 || linrgb[1] < 0 || linrgb[2] < 0) {
        return 0;
      }
      const kR = HctSolver.Y_FROM_LINRGB[0];
      const kG = HctSolver.Y_FROM_LINRGB[1];
      const kB = HctSolver.Y_FROM_LINRGB[2];
      const fnj = kR * linrgb[0] + kG * linrgb[1] + kB * linrgb[2];
      if (fnj <= 0) {
        return 0;
      }
      if (iterationRound === 4 || Math.abs(fnj - y) < 0.002) {
        if (linrgb[0] > 100.01 || linrgb[1] > 100.01 || linrgb[2] > 100.01) {
          return 0;
        }
        return colorUtils.argbFromLinrgb(linrgb);
      }
      // Iterates with Newton method,
      // Using 2 * fn(j) / j as the approximation of fn'(j)
      j = j - (fnj - y) * j / (2 * fnj);
    }
    return 0;
  }

  /**
   * Finds an sRGB color with the given hue, chroma, and L*, if
   * possible.
   *
   * @param hueDegrees The desired hue, in degrees.
   * @param chroma The desired chroma.
   * @param lstar The desired L*.
   * @return A hexadecimal representing the sRGB color. The color
   * has sufficiently close hue, chroma, and L* to the desired
   * values, if possible; otherwise, the hue and L* will be
   * sufficiently close, and chroma will be maximized.
   */
  static solveToInt(hueDegrees: number, chroma: number, lstar: number): number {
    if (chroma < 0.0001 || lstar < 0.0001 || lstar > 99.9999) {
      return colorUtils.argbFromLstar(lstar);
    }
    hueDegrees = mathUtils.sanitizeDegreesDouble(hueDegrees);
    const hueRadians = hueDegrees / 180 * Math.PI;
    const y = colorUtils.yFromLstar(lstar);
    const exactAnswer = HctSolver.findResultByJ(hueRadians, chroma, y);
    if (exactAnswer !== 0) {
      return exactAnswer;
    }
    const linrgb = HctSolver.bisectToLimit(y, hueRadians);
    return colorUtils.argbFromLinrgb(linrgb);
  }

  /**
   * Finds an sRGB color with the given hue, chroma, and L*, if
   * possible.
   *
   * @param hueDegrees The desired hue, in degrees.
   * @param chroma The desired chroma.
   * @param lstar The desired L*.
   * @return An CAM16 object representing the sRGB color. The color
   * has sufficiently close hue, chroma, and L* to the desired
   * values, if possible; otherwise, the hue and L* will be
   * sufficiently close, and chroma will be maximized.
   */
  static solveToCam(hueDegrees: number, chroma: number, lstar: number): Cam16 {
    return Cam16.fromInt(HctSolver.solveToInt(hueDegrees, chroma, lstar));
  }
}
